EP3119661B1 - Steering column for a motor vehicle, threaded rod and spindle nut - Google Patents

Description

Technical area

The present invention relates to a steering column for a motor vehicle, which has a support unit which can be connected to the chassis of the motor vehicle and a positioning unit which is held on this support unit and can be adjusted relative to the support unit by means of an adjustment drive. The invention further relates to a threaded rod and a spindle nut for a drive for adjusting such a steering column.

State of the art

Steering columns for motor vehicles are known, which comprise a connectable to the chassis of the motor vehicle support unit, for example in the form of console parts, and a held on this support unit and adjustable relative to this support unit actuating unit. The actuator supports a steering shaft, which serves to initiate a steering movement of a steering wheel in a steering system for transmitting the steering movement to a steerable wheel.

It is known to design such an adjusting unit relative to the support unit by means of an adjusting adjustable to adjust the position of a held on the steering shaft steering wheel to the respective seating position of a driver of the motor vehicle. It is known to provide an adjustability of the actuator in the axial direction with respect to the steering shaft in order to achieve a longitudinal adjustment of the steering column. Furthermore, it is known to enable a height adjustment of the steering wheel by pivoting the actuator relative to the support unit.

Known adjustment drives include electric motors, by means of which a comfortable adjustment of the setting unit relative to the support unit can be achieved and which also allow the repeated approach pre-stored positions, especially when multiple drivers operate the motor vehicle.

In electrically adjustable steering columns for motor vehicles, it is necessary, the rotation of an output shaft of an electric motor in a translational adjustment for adjusting the Reach actuator relative to the support unit. This is usually done by a threaded rod drive, which comprises a arranged on the output of the electric motor worm shaft and a spindle nut which is formed on its outer side as a worm wheel, engages in the toothing of which arranged on the output shaft of the electric motor worm shaft. By rotation of the stationary spindle nut, the threaded rod is moved axially.

From the generic AT 511962 A4 is known a steering column for a motor vehicle, in which both a displacement of the steering shaft and a pivoting of the steering shaft relative to a support unit can be made to achieve a corresponding positioning of the steering wheel held on the steering wheel. Both adjustment movements, so both the displacement and the pivoting, are achieved via a respective spindle drive. The spindle drives each comprise a threaded rod, which is held by a spindle nut on one of the two mutually adjustable units. The spindle nut is mounted stationary and can be rotated via a drive motor with a worm shaft, which acts on an external toothing of the spindle nut to achieve via an internal thread which engages with the threaded rod, according to a translational movement of the threaded rod with respect to the spindle nut in the direction of the threaded spindle axis , By the translational movement of the threaded rod, the adjustment of the actuator is effected.

It is known to use a metric ISO standard thread for the external thread of the threaded rod and for the internal thread of the spindle nut, which has a flank angle of 60 °. From the DE 36 36 315 A1 an axially adjustable steering column for a motor vehicle is known in which for the external thread of the threaded rod such a thread is shown. When using an ISO standard thread high forces are introduced into the thread flanks by the relatively flat flank angle of 60 °, which can lead to a spreading of the spindle nut or to a compression of the threaded rod and can adversely affect the drive behavior of the adjustment in this way.

Furthermore, it is for example from the EP 2 412 607 A2 known to perform the thread of an adjustment as a trapezoidal thread, for example as an ISO trapezoidal thread having a flank angle of 30 °.

When using an ISO trapezoidal thread, it is disadvantageous apart that the respective threads have a high gear thickness, whereby a relatively large outer diameter of the respective assembly is formed.

Presentation of the invention

Based on the known prior art, it is an object of the present invention to provide a steering column for a motor vehicle with an adjusting drive, as well as a threaded rod and a spindle nut for an adjustment, which provide an improved drive behavior of the adjustment ready.

This object is achieved by a steering column for a motor vehicle having the features of claim 1. Advantageous developments emerge from the subclaims.

Accordingly, a steering column for a motor vehicle is proposed, comprising a connectable to the chassis of the motor vehicle support unit and a control unit held thereon, which supports a steering shaft for transmitting a steering torque from a steering wheel to a steerable wheel, wherein the position of the actuating unit relative to the support unit means an adjusting drive is adjustable, wherein the adjusting drive has a threaded rod with an external thread, which is in engagement with an internal thread of a spindle nut of the adjusting drive. According to the invention, the external thread of the threaded rod and / or the internal thread of the spindle nut has a flank angle between 35 ° and 55 °.

Preferably, the steering spindle can transmit the steering movement of the steering wheel with the interposition of a steering gear and especially with the use of an auxiliary power assistance on the steerable wheel.

But it is also possible that the steering movement of the steering shaft is sensed, for example electrically, electronically or magnetically, and the sampled signals are fed into a controller which performs a device pivoting of the steerable wheel to illustrate the steering movement. Such systems are known as steer-by-wire.

Due to the fact that the external thread of the threaded rod and / or the internal thread of the spindle nut has a flank angle of 35 ° to 55 °, it is possible to spread the To reduce spindle nut during operation or prevent completely, so that accordingly the drive behavior of the adjustment can be improved.

Furthermore, it is possible in this way to achieve the smallest possible thread diameter at a large thread core diameter, since due to the reduced or completely missing Aufspreizens the spindle nut with a low edge height of the thread necessary for adjustment forces can be transmitted. In this way, the operating characteristics of the adjustment can be improved because deformations in the material of the threaded rod and / or the spindle nut can be reduced or avoided altogether. As a result, a reliable operation of an electrically adjustable steering column via the adjustment can be achieved. Furthermore, it can reduce the background noise.

Preferably, the flank angle between 40 ° and 50 ° to keep the spindle nut aufspreizende force components as small as possible, but at the same time to allow easy production of the respective thread, for example by cutting.

Accordingly, the external thread and / or the internal thread is preferably formed as a cut thread. The possibility of cutting the thread makes it possible to resort to different materials for the threaded rod and the spindle nut. Such a relatively free choice of material makes it possible to cut the external thread of the threaded rod and / or the internal thread of the spindle nut in a plastic material, for example, in a plastic material having a fiber reinforcement.

The expression of the flank angle of 35 ° to 55 ° therefore makes it possible, due to the lower Aufspreizneigung to produce the spindle nut completely made of a plastic material, in this way an improved performance of the adjustment, in particular with regard to its vibration and / or vibration behavior, as well in relation to the long-term tribological behavior.

Alternatively and preferably, the thread is directly injected or molded during molding of the spindle. The same applies to the spindle nut.

Preferably, the external thread and / or the internal thread has at least two threads. In this case, the training of a precisely two-start thread is particularly preferable. However, exactly three-start or exactly four threads formed can be beneficial. By training as a multi-thread, a more efficient, faster and more efficient safer positioning of the actuator can be achieved. However, the engine power must be adapted to the correspondingly faster adjustment speed.

Easy manufacturability and a direction-neutral operating behavior of the adjustment drive are obtained preferably when the external thread and / or the internal thread is flank-centered.

The vibration behavior, the tribological behavior and / or the damping behavior of the adjusting drive is set according to the invention, when the threaded rod and the spindle nut have mutually different materials.

In this context, in the embodiment according to the invention, the spindle nut on a plastic material, preferably made of a plastic material having a fiber reinforcement. In this case, the fiber reinforcement can also be formed only in the center of the threaded spindle in order to ensure a high rigidity of the transmission, but at the same time to allow easy insertion of the thread, without breaking the fibers and thus to deteriorate the tribological properties. In particular, glass fibers, carbon fibers or Aramitfasern may be used.

The object described above is further achieved by a spindle nut having the features of claim 7.

Accordingly, a spindle nut for an adjustment for adjusting the position of an actuating unit relative to a support unit of a steering column for a motor vehicle is proposed, comprising an internal thread for engaging in an external thread of a threaded rod.

According to the invention, the threaded rod and the spindle nut on each other different materials, wherein the spindle nut comprises a plastic material, and the internal thread has a flank angle between 35 ° and 55 °. In a preferred embodiment, the flank angle is between 40 ° and 50 °.

The threaded rod and the spindle nut can preferably also be further developed by the features of dependent from claim 1 dependent claims 2-6.

Brief description of the figures

• Figur 1 eine schematische perspektivische Darstellung einer Lenksäule mit einer elektrischen Verstellung;
• Figur 2 die Lenksäule aus Figur 1 in einer schematischen Seitenansicht;
• Figur 3 die Lenksäule aus Figur 1 in einer weiteren schematischen Seitenansicht;
• Figur 4 ein Verstellantrieb für eine Lenksäule gemäß den vorgenannten Figuren in einer auseinandergezogenen Darstellung;
• Figur 5 eine schematische Schnittdarstellung durch eine Gewindestange und eine Spindelmutter eines Verstellantriebs; und
• Figur 6 eine Detailansicht eines Abschnitts des Verstellantriebs aus Figur 5.

Preferred further embodiments and aspects of the present invention are explained in more detail by the following description of the figures. Showing:

• FIG. 1 a schematic perspective view of a steering column with an electrical adjustment;
• FIG. 2 the steering column off FIG. 1 in a schematic side view;
• FIG. 3 the steering column off FIG. 1 in a further schematic side view;
• FIG. 4 an adjustment for a steering column according to the aforementioned figures in an exploded view;
• FIG. 5 a schematic sectional view through a threaded rod and a spindle nut of an adjustment; and
• FIG. 6 a detailed view of a portion of the adjustment from FIG. 5 ,

Detailed description of preferred embodiments

In the following, preferred embodiments will be described with reference to the figures. In this case, identical, similar or equivalent elements in the different figures are denoted by identical reference numerals and a repeated description of these elements will be omitted in the following description in part in order to avoid redundancies.

FIG. 1 shows a steering column 1, which has a connectable to the chassis of a motor vehicle, not shown here carrying unit 10, on which an adjusting unit 16 adjustable is held. The support unit 10 comprises a bracket 100, which can be fastened to the chassis of the motor vehicle, for example via fastening bores 102.

The adjusting unit 16 comprises a jacket tube 12, in which a steering spindle 14 is rotatably mounted. At the steering wheel-side end 141 of the steering shaft 14, a steering wheel, not shown here, can be attached. The steering shaft 14 serves to transmit a steering torque introduced by a driver via the steering wheel onto the steering spindle 14 in a known manner to a steerable wheel (not shown here). The steering shaft 14 can transmit the steering movement from the steering wheel to the steerable wheel with the interposition of a steering gear, optionally with the aid of an auxiliary power assistance.

In a variant, the steering movement of the steering shaft 14 may also be sensed, for example electrically, electronically or magnetically, and fed into a controller which, with the aid of a steering device, performs a pivoting of the steerable wheel to display the steering movement. Such systems are known as steer-by-wire.

The jacket tube 12 is held displaceably in a carrier tube 104 in a longitudinal displacement direction X, the longitudinal displacement direction X extending in the axial direction of the steering spindle 14. By adjusting the casing tube 12 relative to the support tube 104 can be achieved according to a longitudinal adjustment of the steering shaft 14 and thus of the steering wheel, not shown for adjusting the position of the steering wheel to the sitting position of a driver of the motor vehicle.

The support tube 104 is pivotally mounted on the console 100 and can be pivoted about a pivot axis 106 relative to the console 100. An adjustability of the setting unit 16 in a height adjustment direction Z, which is oriented substantially perpendicular to the longitudinal adjustment X, is made possible by the fact that the jacket tube 12 is held by a pivoting mechanism 18 on the console 100. This results in a pivotability of the jacket tube 12 and the steering shaft 14 relative to the support unit 10 and in particular with respect to the console 100 about the pivot axis 106 such that a height adjustment of the steering wheel is not shown here and is arranged on the steering wheel 14 is achieved to also on this Way to achieve an adjustment of the position of the steering wheel to the driver's seating position.

In the exemplary embodiment, a separate adjusting drive 2, 2 ', each with a separate adjusting gear, comprising a threaded rod 4, 4, and a spindle nut 3 for each of the two adjustment directions.

An adjusting drive 2 is provided, by means of which an adjustment of the adjusting unit 16 relative to the support unit 10 in the longitudinal adjustment direction X can be achieved. The adjustment drive 2 comprises a threaded rod 4, which is connected via an articulation lever 120 with the casing tube 12. The articulation lever 120 is displaceably guided in a slot 110 in the support tube 104 such that a displacement of the articulation lever 120 relative to the support tube 104 results in a displacement of the actuation unit 16 relative to the support unit 10.

The threaded rod 4 is held on the articulation lever 120 and extends in the longitudinal displacement direction X. The threaded rod 4 is also held in a spindle nut 3, which has an internal thread 32 which is in engagement with the external thread of the threaded rod 4. The spindle nut 3 is rotatably but fixedly mounted with respect to the support tube 104 in a gear housing 34, so that rotation of the spindle nut 3 due to the threaded engagement with the threaded rod 4 leads to an axial movement of the threaded rod relative to the spindle nut 3. In other words, by a rotation of the spindle nut 3, a relative movement between the casing tube 12 and support tube 104 takes place so that an adjustment of the position of the actuating unit 16 relative to the support unit 10 is effected by the rotation of the spindle nut 3.

The adjusting drive 2 further comprises a drive motor 20, on the output shaft 24 a in FIG. 4 well visible worm shaft 22 is arranged. The worm shaft 22 engages in an outer toothing 30 of the spindle nut 3, wherein the external toothing 30 is formed as a worm wheel. The axis of rotation of the worm shaft 22 and the axis of rotation of the spindle nut 3 are perpendicular to each other, as it is known per se in a worm gear.

Accordingly, the spindle nut 3 can be rotated by a rotation of the output shaft 24 of the drive motor 20, whereby a longitudinal displacement in the longitudinal adjustment X of the actuator 16 relative to the support tube 104 and thus a displacement of the actuator 16 relative to the support unit 10 takes place.

A corresponding adjusting drive 2 'is particularly good in FIG. 3 to recognize. This further adjustment drive 2 'has, in principle, the same construction as the first adjustment drive 2. The Further adjustment drive 2 'drives an adjusting movement of the setting unit 16 in the height adjustment direction Z. About the rotation of a threaded rod 4 ', a spindle nut 3' is displaced in the axial direction. The spindle nut 3 'is connected via a joint 182 with a control lever 181. The adjusting lever 181 is pivotably held in a hinge axis 183 on the support tube 104 and in a hinge axis 184 on the console 100. As a result, it is achieved that the spindle nut 3 'applies a corresponding adjustment to the pivoting mechanism 18 and thus to the setting unit 16 and the support tube 104 via the threaded rod 4'. For a required length compensation, a corresponding compensation function is integrated in one of the joints. In the example, this is represented by a slot recording of a pivot axis 106 forming bolt in the console.

In FIG. 4 the adjusting drive 2 is shown again in a schematic, perspective and exploded view. The drive motor 20 with the output shaft 24, on which the worm shaft 22 is formed, can be seen. The worm shaft 22 is in engagement with the outer toothing 30 of the spindle nut 3 designed as a worm wheel. The spindle nut 3 is fixed in the gear housing 34 and held rotatably about the axis 400 of the threaded rod 4. The spindle nut 3 is not displaceably mounted in the direction of the axis 400 of the threaded rod 4 relative to the support tube 104. The threaded rod 4 is with its external thread 42 into engagement with the internal thread 32 of the spindle nut 3. The gear housing 34 ensures accordingly that are displaced by a rotation of the spindle nut 3 in engagement with this threaded rod 4 in the direction of the axis 400 of the threaded rod 4 can.

The spindle nut 3 and / or the threaded rod 4 may preferably comprise or consist entirely of non-fiber-reinforced plastic, such as, for example, POM (polyoxymethylene), POM homopolymers, DELRIN® 100 NC 010 and / or DELRIN® 100 AL NC 010. The spindle nut 3 and / or the threaded rod 4 may preferably also comprise a fiber-reinforced plastic or consist entirely of a fiber-reinforced plastic, for example POM with carbon fiber and / or PBT (polybutylene terephthalate) with carbon fiber (= carbon fibers).

Sliding additives are particularly preferably added to the plastic material in order to allow self-lubrication of the internal thread 32 of the spindle nut 3 with the external thread 42 of the threaded rod 4 so that a particularly smooth and quiet operation is possible and the tribological properties over the life of the drive 2 substantially be kept the same.

In the FIGS. 5 and 6 a portion of the adjusting drive 2 is shown, in which in particular the threaded rod 4 and the spindle nut 3 can be seen. As already mentioned, the threaded rod 4 has an external thread 42. The external thread 42 is formed in the embodiment shown catchy.

The spindle nut 3 has a to the external thread 42 of the threaded rod 4 complementary internal thread 32, which is in engagement with the external thread 42 of the threaded rod 4.

As can be seen from the detailed representation in FIG. 6 shows, the flank angle α of the external thread 42 of the threaded rod 4 is relatively small and is in the illustrated embodiment at a little below 55 °.

The preferred angular range for the flank angle α is between 35 ° and 55 °. In this way, during a rotation of the spindle nut 3 about the threaded rod 4 around the force component which spreads the spindle nut 3, be reduced compared to the known from the prior art thread forms. As a result, the operating behavior of the adjusting drive 2 is improved compared with the solutions known from the prior art.

Furthermore, it is possible to manufacture the spindle nut 3 from materials or materials other than the materials known from the prior art. In particular, the spindle nut 3 can also be made of a plastic material, which may have improved tribological properties, damping properties and vibration properties compared to conventional materials, so that the operating behavior of the adjusting drive 2 can be further improved.

The external thread 42 of the threaded rod 4 may be cut into the material of the threaded rod 4. This results in that the external thread 42 can be introduced in a simple manner in a wide variety of materials, so that there is correspondingly greater freedom in the choice of material.

By the selected flank angle α and the production of finer threads is possible, so that a simpler manufacturability of both the threaded rod 4 and the spindle nut 3 can be achieved.

Particularly preferably, the external thread 42 of the threaded rod 4 is cut into a plastic material and the threaded rod 4 either completely made of a plastic material, or a plastic material encloses a made of a different material - such as a metal - existing spindle for forming the external thread 42nd

The internal thread 32 of the spindle nut 3 preferably has a complementary to the external thread 42 of the threaded rod 4 geometry. Accordingly, in the illustrated embodiment, the internal thread 32 of the spindle nut 3 has a flank angle α of slightly less than 55 °. The preferred range of the flank angle is here, as well as for the external thread 42 of the threaded rod 4, between 35 ° and 55 °, more preferably between 40 ° and 50 °.

The nominal diameter d of the threaded rod 4 can be reduced by selecting the mentioned flank angle α, which is between 35 ° and 55 °, particularly preferably between 40 ° and 50 °. In particular, the core diameter d _{3 can be} increased, since due to the steeper edges better power transmission takes place and a deformation of the spindle nut 3 and a spreading of the spindle nut 3 is reduced compared to the known from the prior art thread geometries. Accordingly, the same force can be transmitted by means of a thread which has a lower height than the threads known from the prior art. Thus, the core diameter d ₃ relative to a conventional, known from the prior art geometry can be relatively increased, so that either the entire threaded rod 4 can be reduced in its nominal diameter d, or the stability is increased at a given nominal diameter d.

Particularly preferred is a flank-centered thread is used, as in FIG. 5 and FIG. 6 is shown in order to achieve the simplest possible workability or production of the internal thread 32 of the spindle nut 3 and the external thread 42 of the threaded rod 4. Furthermore, an identical drive behavior when adjusting the adjusting drive 2 in both directions of rotation of the spindle nut 3 can be achieved by a corresponding flank-centered thread.

Where applicable, all individual features illustrated in the individual embodiments may be combined and / or interchanged without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

1

steering column

10

support unit

12

casing pipe

14

steering shaft

141

Steering wheel end

16

actuator

18

pivoting

100

console

102

mounting hole

104

support tube

106

swivel axis

110

slot

120

Feedback lever

181

lever

182

joint

183

joint axis

184

joint axis

2

adjustment

2 '

adjustment

20

drive motor

20 '

drive motor

22

worm shaft

24

output shaft

3

spindle nut

30

external teeth

32

inner thread

34

gearbox

34 '

gearbox

4

threaded rod

4 '

threaded rod

42

external thread

44

attack

400

Axle of the threaded rod

α

corner

X

Längsverstellrichtung

Z

height adjustment

d

Nominal diameter

d ₃

K

Claims (7)

1. Steering column (1) for a motor vehicle, comprising a support unit (10) which is connectable to the chassis of the motor vehicle and comprising a positioning unit (16) which is held on said support unit and which serves for the mounting of a steering spindle (14) for transmitting a steering moment from a steering wheel to a steerable wheel, wherein the position of the positioning unit (16) relative to the support unit (10) is adjustable by way of an adjustment drive (2, 2'), wherein the adjustment drive (2, 2') comprises a threaded rod (4, 4') with an external thread (42) which engages with an internal thread (32) of a spindle nut (3) of the adjustment drive (2, 2'),
   characterized in that
   the threaded rod (4) and the spindle nut (3) comprise mutually different materials, wherein the spindle nut (3) comprises a plastics material, and the external thread (42) of the threaded rod (4) and/or the internal thread (32) of the spindle nut (3) comprises a flank angle (α) of between 35° and 55°.
2. Steering column (1) according to Claim 1, characterized in that the flank angle (α) lies between 40° and 50°.
3. Steering column (1) according to Claim 1 or 2, characterized in that the external thread (42) and/or the internal thread (32) comprises at least two thread flights.
4. Steering column (1) according to one of the preceding claims, characterized in that the external thread (42) and/or the internal thread (32) is of flank-centred design.
5. Steering column (1) according to one of the preceding claims, characterized in that the external thread (42) and/or the internal thread (32) is in the form of a cut thread.
6. Steering column (1) according to Claim 1, characterized in that the spindle nut (3) is formed from a plastics material which comprises a fibre reinforcement.
7. Spindle nut (3) for an adjustment drive (2, 2') of a steering column (1), comprising an internal thread (32) for engaging into an external thread (42) of a threaded rod (4, 4'),
   characterized in that
   said spindle nut comprises a plastics material and the internal thread (32) comprises a flank angle (α) of between 35° and 55°.

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